Internal combustion engine



INTERNAL COMBUSTION ENGINE Filed Sept. 14, 1929 Patented Nov. 14, 1933 y g 1,935,171

UNITED STATES lPATENT" OFFICE 1,935,171 INTERNAL CoMUsTroN ENGINE Lionel M. Woolson, Detroit, Mich., assignor to Packard Motor Car Company, Detroit, Mich., a corporation of Michigan Application September 14, 1929 Serial No. 392,629

9 Claims. (Cl. 12S-145) 'I'his invention relates to internal combustion wire with the electrode in a. manner gradually engines and more particularly to devices, known reducing the temperature thereof in a direction as glow plugs, for assisting the combustion of fuel toward its point of attachment thereto. charges in engines of the type in which ignition Another object of my invention is to provide occurs through compression. a glow plug for internal combustion engines in 50 Glow plugs are especially useful for assisting which the resistance wire is associated and atthe starting of Diesel engines, or engines of the tached to the electrode in a rugged manner such Diesel type, in which ignition is caused by comthat a relatively long life thereof is assured. pression. In such devices, a resistance wire, an- Another object of my invention is to provide a 10 chored at one end to the electrode and at the glow plug for internal combustion engines in 65 other end to the body, is usually placed in a rewhich the resistance wire is formed in a manner lation such that the incoming fuel is sprayed so that fuel can be sprayed intimately with a thereagainstv and thus atomized to a greater exlarge incandescent surface. tent than it would be ordinarily. Furthermore, A further object'of my invention is to provide such resistance wire produces a certain degree of a glow plug for internal combustion engines in 70 heat within the combustion chamber in which which an electrode is secured in insulated relathe fuel charge is compressed. As the voltage tion to a carrier body through a novel form of which is usually supplied to glow plugs is necesconnecting means. sarily small, the resistance wire must likewise be Still another object of my invention is to prosmall to produce the maximum heat. vide a glow plug for internal combustion engines 75 Diesel engines ordinarily operate at a comwhich will stand many hours of use with an inpression of approximately 500 pounds per square ternal combustion engine without disarranging inch in the combustion chamber, so that the exthe relative positions of the component elements. plosive shocks and the vibrations caused by ex- These and other objects of the invention will plosions are more noticeable than with engines appear from the following description taken in 80 in which the compression is approximately 150 connection with the drawing, which forms a part pounds per square inch in the combustion chamof this specification, and in which: ber. Furthermore, with engines in which the Fig. 1 is a medial sectional view of a glow plug liquid fuel is sprayed into the combustion chamincorporating my invention, f ber against the glow plug, it will be seen that the Fig. 2 is a side elevational View of the same, 85 heat is centralized upon the glow plug, and that Fig. 3 is a sectional View of the glow plug taken it will therefore develop a higher temperature on line 3-3 of Fig. Land than any of the other elements adjacent thereto. Fig. 4 is a fragmentary sectional view of one It therefore follows that when the resistance wire end of the glow plug illustrating the manner in 0f the glOW plug is connected with a source of which the inner coil of the resistance wire is as- 90 electric supply, that the heat is such as to cause sociated with the electrode. an extreme expansion of both the glow plug wire Referring now to the drawing by characters of and electrode with the result that considerable reference, the core or electrode of the glow plug difiiculty has been encountered because of breakconsists of a cylindrical portion 10, an enlarged 40 age of the wire at its point of attachment with 'portion 11 forming a shoulder 12, and a tapered the electrode. Such breakage being Caused by end portion 13 terminating in a head 14. A tereXDansiOn 0f theY aSSOCieted metals, Causing minal member 15 is arranged at one end of the IOOSening 0f the COnneCtiOns, and aise by the Vielectrode and is retained thereon by a flanged end bration and fuel pressure causing bending mo- 16. Surrounding the electrode intermediate the ments of the resistance wire at its points of conterminal member 15 and the shoulder 12 is a 100 nection. Furthermore, the high temperature cylindrical insulating collar 17 preferably formed developed within the combustion chamber of an of mica, While insulating means 13, consisting of engine 0f this type is Ordinarily SllCh that the inmica discs, surrounds the end of the collar adja- Candeseent Wire Of the glow plug will be maincent the shoulder 12. A plurality of mica discs 19 tained in a glowing condition even when the consurround the collar 17 and extend intermediate 105 nection from the source of electric supply thereto the terminal member 15 and the supporting struchas been switched off, and the above related unture for the electrode. desirable conditions will still exist. The supporting structure for the electrode con- An object of my invention is to increase the sists of a metal body 20, a wedge nut 21, and a life of glow plugs by associating the resistance tapered sleeve 22. The tapered sleeve surrounds 110 the collar 17 and in turn is surrounded by the nut 21 which is provided with a tapered interior surface adapted to cooperate with the tapered exte rior `surface of the sleeve 22. The tapered nut 21 is arranged to be screwed into one end of the body 20. In this manner the sleeve 22 can be drawn against the insulating discs 18 tightly pressing them against the shouldered portion 12 of the electrode and as the mica discs 19 extend intermediate the sleeve 21 and the terminal 15, the electrode is thereby held securely with the housing. A copper gasket 9 is compressed intermediate the inner end of the nut and a shoulder portion of the body.

The body is provided with an exteriorly threaded end which is adapted to be screwed into an aperture in the wall of a cylinder of an internal combustion engine. The other end of the body is formed with ilat surfaces such that a wrench can be applied thereto for screwing the body into and out of the aperture in the cylinder wall. The body 20 is hollow and is of an interior diameter considerably greater than the diameter of the enlarged portion of the electrode which extends therein. The tapered portion of the electrode projects through the end of the housing and a resistance wire 23 is associated with the electrode and with the body. One end 24 of the resistance Wire extends through a diagonally extending opening 25 in the enlarged portion 11 of the electrode and is homogeneously secured at its end to the electrode, as shown at 26, by welding or some similar securing means. A plug 2'7 extends transversely through one end of the section 11 of the electrode and is arranged so that it will wedge a portion of the resistance wire, extending through lthe diagonal slot, firmly against the electrode. The other end of the resistance wire extends into a recess 27 in the end of the body 20 and is secured therein by the plug 28 which projects into the recess and switches the wire against the body.

The resistance wire 23 is formed in two spaced nesting coils, a portion of each of which surround the tapered portion of the electrode and the inner coil 29 being wound closely around the projecting end of the electrode. The convolutions of the inner coil of the wire become relatively closer together toward the head of the electrode so that two or three convolutions will tightly encircle the tapered end of the electrode in a close relation, and will be maintained in such position axially by the electrode head 14. Such convolutions then continue in increasing diameter and project over and beyond the end of the electrode head where they merge into the exterior coil portion 30 of the wire structure. The central convolution oi the outer coil is largest and the convolutions gradually reduce in diameter therefrom. It will be understood that the terminal 15 is adapted to be connected to a source of electrical supply, one terminal of which is grounded, and that the body 20 is screwed into the wall of the cylinder so that the portion of the electrode and the resistance wire projecting beyond the end of the body will lie interiorly of the cylinder of an internal combustion engine. It will be seen that one end of the wire is grounded through being attached to the body 20 while the other end of the wire is connected to the source of the electrical supply by a suitable wiring including a switch mechanism, not shown, connected to the terminal 15.

Ordinarily, glow plugs are energized only in starting an engine, however, they may also be used while the engine is in operation if desired. When in contact with the source 0f electrical SUP- ply the resistance wire 23 produces heat, and spraying of liquid fuel thereagainst materially assists in vaporizing the fuel, thereby promoting starting the engine. Such heat also assists in raising the temperature within the cylinder.- As Diesel type engines, with which this invention is particularly adapted to be associated, usually operate at a high compression, approximately 500 or more pounds per square inch in the combustion chamber, and the fuel is injected at a high pressure, usually approximately 2,000 or more pounds, concentration of the fuel upon the resistance wire and the high compression pressure, will maintain the resistance wire in a glowing condition even when the connection with the source of electrical supply is switched off. It will, therefore, be seen that the resistance wire is subjected to intense heat during starting or running of the engine, and that such heat centralizes upon the point of attachment with thel electrode.

Glow plugs heretofore known to me have failed after short usage, principally because of the breakage of the resistance wire at the point of its connection with the electrode. This breakage is caused by the wire temperature and vibration, the temperature of the wire being substantially maximum at the point of its attachment to the electrode permits breakage by bending moments resulting from vibration. This breaking condition is not so marked with the wire at its attachment to the body because of the high heat differential which will cause an increasing decrease in the wire temperature approaching the connection. It will be seen that I have provided an association of a resistance wire with an electrode such that the wire temperature gradually decreases toward the end attached to the electrode and in which vibration at the connection is substantially eliminated. The manner of fastening the wire extend ing through the opening in the electrode by wedging and welding is also of material assistance in preventing separation of the wire from the electrode.

It will be seen that I have provided a highly eiiicient structure which is simple in form, and which can be readily assembled when manufacturing. It also will be seen that the resistance wire is such that it will withstand extensive use with engines of the Dieseltype, and without increasing its size or the voltage required to produce the requisite heat.

While a specic embodiment of the invention has been herein described, which is deemed to be new and advantageous and may be specically claimed, it is not to bev understod that the invention is limited to the exact details of the construction, as it will be apparent that changes may be made therein without departing from the spirit or scope of the invention.

What I claim is:

1. In a glow plug for internal combustion engines having a body and an electrode projecting from the body, the projecting end of the electrode being formed with a head, heating means comprising a resistance wire secured at one end to the electrode and secured at the other end to the body, the portion of the wire adjacent the end secured to the electrode being Wound closely around and engaging against the projecting end of the electrode in convolutions which are closer toward the electrode head.

2. In a glow plug for internal combustion engines having a body and an electrode carried by and insulated from the body, heating means comprising a resistance wire rigidly secured at one end to said electrode and at the other end to the body, said wire being coiled about and closely engaging said electrode from its point of attachment thereto for an appreciable distance, and the remainder of said wire forming the major ncandescent portion of the glow plug.

3. In a glow plug for internal combustion engines having a body and an electrode insulated from the body, heating means comprising a resistance Wire, one portion of the wire being attached to the body and another portion of the wire being coiled against the electrode and secured thereto, the wire intermediate said portions forming an incandescent section which is coiled away from the end of the electrode in convolutions increasing in diameter.

'4. In a glow plug for internal combustion engines having a body and an electrode insulated from the body, heating means comprising a resistance wire, one end of the wire being secured to the body, and the other end portion of the wirey being coiled against the end of the electrode, the major portion of the wire intermediate the body and the electrode Vforming an incandescent section.

5. A glow plug for internal combustion engines having a body and an electrode projecting Abeyond one end of the body, the projecting end of said electrode terminating in a head, heating means comprising a resistance wire fixed at one end to the body and at the other end to the electrode adjacent the body, said wire comprising an interior coil, surrounding and bearing against the electrode between the end connection thereto and the head, and an exterior coil between the head and the end connection to the body spaced from the interior coil.

6. A glow plug for internal combustion engines having a body and an electrode insulated and projecting from the body, an ignition element comprising a resistance wire formed in two nested coils, the inner coil of said wire encircling and closely engaging the projecting end of the electrode, one end of said wire being secured to the electrode and the other end of the wire being secured to the body.

7. A glow plug for internal combustion engines having a body and an electrode insulated and projecting from the body, an ignition element comprising a resistance wire formed in two spaced coiled portions encircling and projecting beyond the projecting end of the electrode, the ends of said wire being secured one to the body and the other to the electrode.

8. In a glow plug for internal combustion engines having a body and an electrode extending from the body, a heating element comprising a resistance wire formed with two nested coiled portions,'the outer of which is openly wound, the inner coiled portion of the wire surrounding and extending beyond the projecting end of the electrode andthe ends of the wire being secured one to the electrode and the other to the body.

9. In a glow plug for internal combustion engines having a body, an electrode having intersecting apertures therethrough, a resistance wire having one end secured to the body and the other end extending through one of the apertures, and a pin extending through one of the apertures in the electrode, said pin wedging the wire in the aperture with the electrode.

LIONEL M. WOOLSON. 

